A new model of competition, where competition is among supply chain networks rather than individual firms, is transforming traditional market-based buyer-supplier relations to one of competition among cooperative sets. In order to integrate and realize performance gains from participating in cooperative supply networks, the importance of information sharing across the supply chain has been emphasized in different literature streams. In this study, we examine the relational antecedents of this critical aspect of supply chain integration—that is, information flow integration. Our objective is to investigate the relationship between relational orientation of the focal firm, as characterized by (1) long-term orientation of its supply chain relationships, (2) asset specificity, and (3) interaction routines and the information flow integration between a firm and its supply chain partners. A research model was developed and data were collected from 110 supply chain and logistics managers in manufacturing and retail organizations. Our results suggest that tangible and intangible resources invested in supply chain relationships enable the integration of information flows with supply chain partners. Specifically, formal and informal interaction routines that take time and effort to develop enable integration of informational flows across a firm's supply chain. Investments in relation-specific assets and long-term orientation in relationships enable the development of these interaction routines.